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Method of avoiding synchronization between communicating nodes

a communication node and synchronization technology, applied in the direction of synchronisation signal speed/phase control, data switching network, synchronisation arrangement, etc., can solve the problems of collisions between transmissions, attendant problems of collisions, and above solutions that are not entirely satisfactory, so as to avoid collisions in the communication system

Inactive Publication Date: 2005-09-01
OKI ELECTRIC IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for avoiding collisions in a communication system by autonomous control of communicating nodes. The nodes can adjust flexibly and autonomously to changing conditions in the communication system. The invention also allows for flexible allocation of bandwidth among nodes. The invention provides a node that transmits a state variable signal to another node, which causes a periodic operation at the receiving node at a timing related to the state variable signal. The timing decision unit adjusts the timing of the periodic operation so that it is mutually distanced from the timings of other periodic operations performed at other nodes. The invention also allows for the addition of new nodes without disrupting the existing network. Each node performs its periodic operation at a basic rate determined by its processing capability and other factors. The invention provides a machine-readable medium and a method for controlling nodes in a network.

Problems solved by technology

In a wireless network, since the nodes share a common communication medium, sometimes referred to as an air interface, they face a problem of collisions between transmissions from different nodes.
Wired networks such as local area networks may also have a common transmission medium such as a shared cable, with the attendant problem of collisions.
The above solutions are not entirely satisfactory.
In the TDMA system, if the central server fails, all of the nodes under its control lose the capability to communicate.
This is generally a complex process, and is difficult to carry out rapidly when there are many nodes generating traffic at once.
In the CSMA / CA and CSMA / CD systems, as the number of nodes generating traffic increases, so does the amount of overhead included in the traffic, causing an unavoidable loss of communication efficiency.
Transmission collisions, which occur when two nodes transmit simultaneously on the same communication medium, are just one example of the more general problem of unwanted synchronization between nodes.
Even though the router nodes are interconnected by separate cables, if they become synchronized and all transmit routing information at the same times, the network becomes overloaded at these times and communication may be delayed, or data may be lost.

Method used

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  • Method of avoiding synchronization between communicating nodes
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  • Method of avoiding synchronization between communicating nodes

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Experimental program
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first embodiment

[0034] Referring to FIG. 1, a first embodiment of the invention comprises a plurality of spatially distributed nodes A that exchange data by wireless communication.

[0035] As shown in FIG. 2, each node A comprises an impulse signal receiving unit 11, a communication timing controller 12, an impulse signal transmitter 13, a steady-state decision unit 14, a data communication unit 15, and a sensor 16. Each node A also has a power supply (not shown) for supplying electrical power to these components.

[0036] The impulse signal receiving unit 11 receives an input impulse signal Sin11 and outputs a received impulse signal Spr11 to the communication timing controller 12 and the steady-state decision unit 14.

[0037] The communication timing controller 12 generates a phase signal Spr12 and outputs it to the impulse signal transmitter 13, steady-state decision unit 14, and data communication unit 15.

[0038] The impulse signal transmitter 13 outputs an output impulse signal Sout11 to the outsi...

second embodiment

[0099] Next, a node according to a second embodiment of the invention will be described. Referring to FIG. 6, the second embodiment adds a suspension controller 10 to the node structure in the first embodiment. The suspension controller 10 outputs a suspend signal Spr10 to all the other constituent elements of the node, that is, to the impulse signal receiving unit 11, communication timing controller 12, impulse signal transmitter 13, steady-state decision unit 14, data communication unit 15, and sensor 16.

[0100] The second embodiment operates in the same way as the first embodiment, except for the following differences.

[0101] The suspension controller 10 switches the operation of each other constituent element in the node on and off periodically. The impulse signal receiving unit 11, communication timing controller 12, impulse signal transmitter 13, steady-state decision unit 14, data communication unit 15, and sensor 16 operate when the suspend signal Spr10 is in the on-state, a...

third embodiment

[0108] Next, a third embodiment of the present invention will be described. Referring to FIG. 7, a node in the third embodiment comprises a data pulse signal receiving unit 31, a communication timing controller 32, a steady-state decision unit 33, a data pulse signal transmitter 34, and a sensor 35.

[0109] The data pulse signal receiving unit 31 receives an input data pulse signal Sin31, outputs a received impulse signal Spr31 to the communication timing controller 32 and steady-state decision unit 33, and outputs a received data signal Spr31 to the data pulse signal transmitter 34. The communication timing controller 32 outputs a phase signal Spr33 to the steady-state decision unit 33 and the data pulse signal transmitter 34. The steady-state decision unit 33 outputs a steady-state decision signal Spr34 to the data pulse signal transmitter 34. The data pulse signal transmitter 34 sends an output data pulse signal Sout31 to the outside world. The sensor 35 inputs environmental infor...

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PUM

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Abstract

Communicating nodes in a network exchange state variable signals indicating the timing of periodic operations performed at the nodes. Each node autonomously controls the timing of its periodic operation so as to distance the timing from the timing of the periodic operations performed at other nodes. If the periodic operations include data transmission, this arrangement enables the nodes to avoid data collisions. The nodes can also adapt autonomously to changing conditions such as changing priority levels and the addition and removal of nodes.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a system such as, for example, a sensor network, a mobile communication network, or a local area network (LAN) having a plurality of communicating nodes. More particularly, the invention relates to the avoidance of unwanted synchronization between nodes, and the avoidance of collisions between transmissions from different nodes. [0003] 2. Description of the Related Art [0004] The nodes of concern in the present invention are intelligent devices such as computers, personal digital assistants (PDAs), mobile telephones, or so-called smart sensors, having computational capabilities as well as communication capabilities. Networks of such nodes have become widespread. [0005] In a wireless network, since the nodes share a common communication medium, sometimes referred to as an air interface, they face a problem of collisions between transmissions from different nodes. Two well-known soluti...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04L7/08H04L12/28H04L12/413H04W56/00H04W72/04H04W74/04H04W74/08H04W84/12H04W84/18
CPCH04L7/08H04W74/0816H04W56/00H04L12/407
Inventor DATE, MASAAKIMORITA, YUKIHIROTANAKA, HISAAKI
Owner OKI ELECTRIC IND CO LTD